drm/amdgpu: explicitly sync VM update to PDs/PTs

Explicitly sync VM updates to the moving fence in PDs and PTs.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>